Signaling system



- Patented Dec. 15, 1925.

UNITED STATES PATENT OFFICE.

JOHN BURKHOLDER, JR., WEST END, NORTH CAROLINA, ASSIGNOR T0 WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OI NEW YORK.

SIGNALING .BYSTEH.

Application filed April 17, 1922. Serial No. 554,054.

To all whom it may concern Be it known that 1, JOHN C. BURKHOLDER,

J r.,'a citizen of the. United States, residing at West End, in'the county of Moore, State of North Carolina, have invented certain new and useful Improvements in Signaling Systems, of which the following is a full,

clear, concise, and exact description.

This invention relates to signaling systems and more particularly to telegraph systems.

In telegraph systems of previously known types it is possible, without the receiving operator being notified of the fact, for the sending operator to continue to send for some time during which no signals get through to the receiving operator due to trouble in some intermediate ap aratus.

\Vhen this occurs the lost part of t e message has to be repeated requiring extra time and energy.

An object of the present invention is-to overcome this disadvantage by providing a system whereby a receiving operator at a receiving station, or an attendant at an intermediate station, is automatically not-i.- fied when a failure to receive signals is due to trouble in the intermediate circuits. Another ob'ect is to provide such an automatic system or a carrier telegraph system to notify the attendant at the carrier terminal of any trouble in the carrier circuits. Other objects will a pear from the description hereinafter to ibllow.

One embodiment of the invention in a carrier telegraph system is characterized by a slow-releasing relay at the receiving carrier terminal station which, normally energized by incoming carrier current, is deenergized to light a signal lamp if no current is received for a predetermined period of time longer than the normal intermission between signal impulses. At the transmitting carrier termlnal station another slow releasing relay functions to cause the transmission of carrier current, if for any reason the sending operator fails to transmit signal impulses in a predetermined manner. Bythe interaction of these two relays the signal atthe receiving carrier terminal is operated only u on the failure of some apparatus located etween the two relays.

be drawing illustrates this embodiment of the invention. The invention, however, is clearly applicable to other types of telegraph or signaling systems.

Referring now to the drawing, a sending subscribers telegraph station, A: is arranged to control the transmission of carrier currents over the transmission line ML for the transmission of signals to a cooperating re- C 81VlIlg' station at the distant end of that line. A receiving station B, similar to the distant receiving station, is arranged to receive signals originating at a distant sending station similarto the station A.

The carrier terminal apparatus controlled by the sending subscriber at station A comprises an oscillator O, a sending am lifier TA, and a sending selective circuit TS connected to the line ML through a balanced transformer 5 with its balancing network N. A polar relay 6 is directly controlled by the key 7 at station A which is connected in series with a subscribers line LS and bat teries 12 and 13. A sounder 11 is located at the subscribers station A. At its upper back contact, rela 6 effects the closure of a short circuit for t e input circuit of the amplifier TA. When this short-circuit is closed current from the oscillator O is prevented from being impressed upon the line ML. At its lower contact relay 6 controls a 'series circuit comprising a battery 10, neutral sounder 8 and slow-releasing relay 9. The neutral sounder 8 is used for monitoring purposes at the carrier terminal station. Relay 9, at its front contact, also controls the short-circuit for the amplifier TA, hereinbefore described. The function of slow-releasing relay 9 will herein- 7 subscribers station E, operates the sounder 19. Slow-releasing rela 20 is connected between the battery 17 an one side of the line the preferred ap LR, the junction point 21 between one winding terminal of the relay 20 and one terminal of the battery 17 being connected to the back contact of receiving-relay 15. Relay 20, at its back contact, closes the c1rcu 1t of signal lamp 22 which is connected in series with battery 23. The function of the slow-releasing relay 20 will be explained hereinafter in connection with the operation of the system.

Any suitable type of apparatus may be used for the oscillator O, transimttm amplifier TA, transmitting selective clrcuit TSC, receivin selective circuit RSO, receiving ampli er RA, and detector D, but aratus is that described in connection wit Fig. 55 of apaper by Messrs. Colpitts and Blackwell on Carrier current telephony and telegraphy, published in the Journal of the American Institute of Electrical Engineers for April, May and June 1921. The oscillator, amplifiers, and detector are electron discharge devices, while the selective circuits are loosely coupled sharply-tuned circuits. The selective circuits, if desired, may comprise band filters of the type described in Patent No.

-1,227,113 issued to G. A. Campbell May In the drawing a single transmitting circuit and a single receiving circuit are shown in detail. For multiplex operation other circuits-may be connected to the line ML through the balanced transformer 5 at the points indicated by dotted lines. The manner of connecting these circuits will be clear without further description. While these additional circuits are similar to the ones shown, it is to be understood that characteristic frequencies are used for each transmitting circuit and its cooperating receiving circuit and that theelectrical con- W stants of the circuits will therefore necessarily differ from each other.

Resistances 30, 31, 32 and 33 in the transmitting circuit and resistances 35, 36, 37, 38 and 39 in the receiving circuit add such impedance values to the several circuits that suitable current for operatin the several relays and Sounders is availa le under all operating conditions. A polar sounder 40 connected in series relationship with a resistance 41 is provided for monitoring purposes at the receiving carrier station.

The 0 eration of the system will now be described by assuming that the subscriber at sending station A is communicating with a cooperating receiving station at the distant end of line ML, which receiving station is similar to the receiving station illustral'led in the drawing. Current is normally transmitted by the signaling apparatus after the manner of closed circuit Morse telegraph operation. In a manner well known, telegraphsignals are transmitted over the line LS- by the operation of key 7. With the key in the closed position shown batteries 12 and 13 are connected in series aiding with respect to the winding marked of polar relay 6, and series opposing with respect to the winding marked Under these circumstances the upper contact of relay 6 is opened and the lower contact closed. If key 7 is opened the circuit for battery 13 is opened and battery 12 supplies current to the winding marked of relay 6, there being no current through the winding marked Under this condition the lower contact of relay 6 is opened while the upper contact is closed. As the key 7 is alternately opened and closed for the transmission of signals, the armature of relay 6 alternately changes positions. With the upper contact of relay 6 opened the oscillator O impresses current on rthe line ML through the amplifier TA. With the upper contact of relay 6 closed the amplifier is short-circuited and no current from the oscillator is supplied to the line ML. Thus, in response to impulses of unidirectional current in the line LS, impulses of carrier current are impressed upon the line ML. Referring to the receiving circuit of the drawing for the effect of these impulses on the cooperating receiving circuitLat the distant end'of the line ML, the receiving relay 15 vibrates in response to these impulses due to the wellknown action of the detector D, the incoming carrier waves causing an increase in the average value of the space current. Incoming carrier current causes the relay 15 to close its front contact. In this position current from batteries 16 and 18, which are connected in series aiding with the line LR, flows through the receiving sounder 19. hen no carrier current is incoming, the back contact of relay 15 is closedand no current flows over the line LR since the batteries 17 and 18 are connected in series opposing relationship with each other through the line LR and sounder 19. Thus, impulses of carrier current incoming from the line ML are repeated as impulses of unidirectional current over the line LR to actuate the soundrli).

When carrier current is incoming from the line ML, the batteries 16 and 17 are connected in series aiding relationship in a circuit passing through the winding of slowreleasing relay 20. The back contact of relay 20 is kept open and the lamp 22 is not lighted. When the back contact of relay 15 is closed during the intermission between impulses of signaling current, the winding of relay 20 is short-circuited and it tends to become deenergized. Since this relay is slow-releasing, its armature is not released before another impulse of signaling current closes the front contact of relay 15 in It is evident that the lamp would also be lighted iffor any reason the subscriber at station A should keep the key 7 open long enough for the slow-releasing relay 20 to' operate. To guard against this contingency slow-releasing relay 9 at the transmitting carrier terminal is provided. Relay '9 releases in a somewhat shorter period of time than relay 20. As has been explained, the lower contact of relay 6, which controls the energizing circuit of relay 9, is opened when key 7 is opened. If the key is held opened therefore for a period of time longer than required for the slow-releasing relay 9 to release, the short-circuit about the amplifier TA will be opened at the front contact of relay 9 and carrier current will be transmitted to the receiving station, and the deenergization of the slow-releasing relay 20 at that station will be prevented.

For commercial purposes a releasing period of twenty seconds for relay 20 and of fifteen seconds for relay 9 would be satisfactory. In the normal operation of a system of this kind, the'time between impulses of si naling current is very much less than fii teen seconds. With a twenty second re leasing time for relay 20 only a very small part of a message could be transmitted by the sending subscriber at station A without its being received by the receiving subscriber at station B before the attendant at the receiving carrier terminal would be automatically notified. Both relays 9 and 20 are. designed to be quick operating in order that the system may be quickly restored to operating condition after any trouble has been cleared.

The application of this invention to ordinary telegraph circuits Will be obvious to those skilled in the art and a detailed description, therefore, will not be given. It is to be understood, however, that suchapplication is within the purview of this invention and that the scope of the invention is to be-limited only by the appended claims.

\Vhat is claimed is:

1. In a telegraph system, means to transmit continuous waves and interrupted wave-s alternatively, a medium over which said waves are transmitted, a receiving device responsive to said waves, and means actuated in response to the received waves and having a predetermined time delay action If no carrier current is incomfor giving an indication when waves fail to be received from the transmitting means for such predetermined time.

2. In a telegraph system, a transmitting station for transmitting signal impulses, a line over which said impulses are transmitted, a receiving station having means responsive to said impulses, a station intermediate said transmitting and receiving stations, and means at said intermediate station pulses, a line over which said impulses are, transmitted, a receiving station having means responsive to said impulses, a station intermediate said transmitting and receiving stations, a slow-releasing relay at said intermediate station actuated by current received at said station continuously or as signal impulses and released at the end of a predetermined period of time after current is discontinued, and a signal actuated by said slow-releasing relay.

4. In a telegraph system, a transmitting station for transmitting signal impulses, a line over which said impulses are transmitted, a receiving station having means responsive to said transmitted impulses, transmitting means at an intermediate station to repeat impulses originating at said transmitting station, a second repeating station to transmit impulses to the receiving station received from said first repeating station, and means at first said station operative to transmit current continuously to said second station after no current has been received from the transmitting station for. a predetermined length of time.

5. Ina carrier telegraph system, a transmitting station adapted to transmit im- \pulses of unidirectional current, a carrier terminal station at which said impulses of unidirectional current are translated into trains of carrier waves, a medium over which said trains of carrier waves are transmitted, a second carrier terminal station at which said trains of carrier waves are translated into impulses of unidirectional current, a receiving station having means responsive to said unidirectional impulses of current, and means at said second carrier station to actuate a signal if carrier waves cease to be received for a predetermined period of time somewhat longer than the normal period between signaling impulses sent out from the sending station.

6. In a carrier telegraph system, a transmitting station adapted to transmit impulses of unidirectional current, a carrier terminal station at which said impulses of unidirectional current are translated into impulses of carrier current, a medium over which said impulses of carrier current are transmitted, a second carrier terminal station at which said impulses of carrier current are translated into impulses of unidirectional current, a receiving station having means responsive to said unidirectional impulses of current, and means at said first carrier terminal station operative to cause the transmission of carrier current continuously to said second carrier station in case unidirectional current ceases to be received from said transmitting station for a predetermined period of time. v,

7. In a carrier telegraph ystem, a transmitting station adapted to transmit impulses of unidirectional current,a carrier terminal station at which said impulsegof unidirectional current are translated into impulses of carrier current, a medium over which said impulses of carrier current are transmitted, a second carrier terminal station at which said impulses of carrier current are translated into impulses of unidirectional current, a receiving station having means responsive to said unidirectional impulses of current, means at said second carrier station actuate a signal if carrier current cease to be received for a predetermined period of time somewhat longer than the normal period between signaling impulses sent out from the sending station, and means at said first carrier terminal station operative to cause the transmission of carrier current continuously to said second carrier station in case unidirectional current ceases to be received from said transmitting station for a predetermined period of time.

8. In a carrier telegraph system, an impulse transmitter, a main line, a repeater for. translating the impulses into carrier wave mitting station and a receiving station joined by a conducting medium, means at said transmitting station for applying continuous waves and interrupted waves alternatively to said medium, means at said receiving station responsive to said waves, a slow-releasing relay controlled by said responsive means adapted to remain energized during the normal reception of said Waves and adapted to be deenergized upon the failure of such waves for a predetermined time, anld an indicating device controlled by said re ay.

10. A telegraph system comprising a transmitting station and a receiving station joined by a conducting medium, means at said transmitting station for applying signaling impulses to said medium, means at said receiving station res onsive to said impulses, means controlled y said responsive means for giving an indication upon the failure of signaling impulses for a predetermined time, and means at said transmitting station for applying a continuous wave to said conducting medium upon the failure of signaling impulses for a shorter period of time than that required to operate said indicating means.

In witness whereof, I hereunto subscribe my name this 14th day of April, A. D., 1922.

JOHN G. BURKHOLDER, JR. 

